This PR adds OMP runtime support for more efficient partitioning of
certain types of collapsed loops that can be used by compilers that
support loop collapsing (i.e. MSVC) to achieve more optimal thread load
balancing.
In particular, this PR addresses double nested upper and lower isosceles
triangular loops of the following types
1. lower triangular 'less_than'
for (int i=0; i<N; i++)
for (int j=0; j<i; j++)
2. lower triangular 'less_than_equal'
for (int i=0; i<N; j++)
for (int j=0; j<=i; j++)
3. upper triangular
for (int i=0; i<N; i++)
for (int j=i; j<N; j++)
Includes tests for the three supported loop types.
---------
Co-authored-by: Vadim Paretsky <b-vadipa@microsoft.com>
A few places in the loop collapse support code make small dynamic allocations
that introduce a noticeable performance overhead when made on the heap.
This change moves allocations up to 32 bytes to the stack instead of the heap.
Differential Revision: https://reviews.llvm.org/D158220
On some platforms, std::abs may inadvertently pull in a math library.
This patch replaces its use in the new loop collapse code with
a no thrills in-situ implementation.
Differential Revision: https://reviews.llvm.org/D150882
MacOS build of LLVM with OpenMP enabled fails with an error
that it doesn't know what std::abs is. Fix by including <cmath>
so that the relevant function declaration is included.
No functional change intended.
Reviewed By: tianshilei1992
Differential Revision: https://reviews.llvm.org/D150687
Fixes a GCC build issue (an instance of unallowed typename keyword) and reworks memory allocation
to avoid the use of C++ library based primitives ) in and restores the earlier commit https://reviews.llvm.org/D148393
Differential Revision: https://reviews.llvm.org/D149010
This patch caused failures on the OpenMP buildbots as discussed in
https://reviews.llvm.org/D149010. We will need to investigate why we are
seeing unresolved references to the standard C++ library.
This reverts commit 5a15ca7f10bcba55a2f51281b1562cf5095ae015.
(rectangular and non-rectangular loops)
Submitting on behalf of Natalia Glagoleva <natgla@microsoft.com>
Differential Revision: https://reviews.llvm.org/D148393
